Lamp bases provide the support for internal lamp components and the electrical connection to those internal components. The usual lamp base associated with the common incandescent lamp, as well as other types of lamp, comprises two electrically conductive portions (a shell and an eyelet) joined by an electrically insulating portion of glass. The shell portion contains means for mating with a socket and, generally, this means comprises a series of threads.
For many years these lamp bases have been manufactured by an automated process whereby the shell and eyelet were positioned at a work station in a spaced apart manned and molten glass was inserted into the space between the shell and the eyelet. A forming tool was inserted into the shell to form the glass, leaving an aperture for a connecting wire to subsequently be inserted to make electrical connection to the eyelet. The shell was formed with an internal annulus about which the glass was adhered.
While this process has been used with great success, a problem has existed with excess glass being deposited within the shell and about the internal annulus. This excess glass is known as flashing and, during subsequent shipping of the bases to customers, the flashing, in the form of glass chips, can break off and cause later contamination in the lamp-making process.